Telecommunications

ABSTRACT

A billing center for a mobile communications system is provided which allows groups of subscribers sharing a single account to be identified both during the call rating procedure, during which call detail records are related to add a charge to the call detail record, and/or to add a usage of a pre-paid usage allocation to be added to the call detail records, and during the production of billing details at the end of a billing period.  
     A relational database holds usage allocation records which pertain either to a single subscriber, or to a group of subscribers. The group of subscribers may consist of any of 2 to 50, or more, subscribers, depending on the subscription type held by the group.

[0001] This invention relates to telecommunications, and in particularapparatus and methods for generating billing data for subscribers in atelecommunications system.

[0002] In mobile communications systems, such as cellular telephonenetworks, billing is conventionally carried out on asubscriber-by-subscriber basis. Herein, the term “subscriber” refers tothe person authorised to access a mobile communications system, using amobile station or a fixed station.

[0003] In a GSM system, when a subscriber utilises a mobilecommunications resource, such as conducting a voice call, sending a fax,retrieving voicemail messages, sending text messages, etc, a call detailrecord is produced in the network which is sent to a billing centre.

[0004] At the billing centre, the call detail records are loggedon-line, and periodically transferred to an off-line billing system, forexample on magnetic tapes. The call detail records are rated to attach acharge to each usage recorded in the call detail records. This chargedepends on the type of service utilised, the length of a connectionutilised, and may also depend on the particular type of subscriptionwhich the subscriber holds.

[0005] At the end of a billing period, for example at the end of eachmonth, the rated call detail records are processed on asubscriber-by-subscriber basis to produce an individual bill for eachsubscriber.

[0006] However, this conventional method of billing implemented in thebilling centre is not particularly convenient for customers havingmultiple subscribers utilising the mobile communications system. It canbe difficult to manage costings for a group of subscribers whenindividual bills are separately received.

[0007] U.S. Pat. No. 4,979,207 proposes a cellular telephone billingsystem which processes call detail records of calls made by subscribersbelonging to multiple-subscriber customers to produce bills. The calldetail records are processed to attach a key identification number foreach subscriber. The key identification number and a chosen associatedinformation format are used to select a type of billing report requiredby the customer so that it may be provided during billing. However, thisonly provides a way to produce a desired format of billing report for acustomer, and does not affect the charge made to a customer.

[0008] It would be desirable to provide apparatus whereby chargingstructures which are flexible, easy to understand, and logical, may beimplemented for associated groups of subscribers in a mobilecommunications system.

[0009] In accordance with one aspect of the invention there is providedapparatus for generating billing data for subscribers in atelecommunications system, said apparatus comprising:

[0010] data storage means for holding subscriber records for a pluralityof groups of subscribers, each of said groups comprising a plurality ofsubscribers for which a combined subscription is held, said groupscomprising different numbers of subscribers; and

[0011] data processing means for analysing call data and applying one ofa number of different predetermined call charging tariffs to a call madeby a subscriber in one of said groups, in dependence on the group ofwhich the subscriber is a member, in order to generate charging data forsaid call.

[0012] This aspect of the invention allows a common charging tariff tobe applied for each subscriber in a group for which a combinedsubscription is held, for example by a business concern.

[0013] According to a further aspect of the invention there is providedapparatus for generating billing data for subscribers in atelecommunications system, said apparatus comprising:

[0014] data storage means for holding subscriber records for a pluralityof groups of subscribers, each of said groups comprising a plurality ofsubscribers and said groups comprising different numbers of subscribers;and

[0015] data processing means comprising means for relating respectiveusage allocations to each said group, each said allocation being sharedby subscribers in the related group.

[0016] This aspect of the invention provides apparatus whereby a usageallocation may be allocated not only to a single subscriber, but bygroups of subscribers of various sizes, thereby allowing flexibility andthe utilisation of usage allocations in accordance with the desires ofdifferent groups of subscribers.

[0017] According to a yet further aspect of the invention there isprovided apparatus for generating billing data for subscribers in amobile communications system, said apparatus comprising:

[0018] data storage means for storing subscriber records and usageallocation records, said usage allocation records being shared byrespective groups of subscribers, each said group comprising a pluralityof subscribers; and

[0019] data processing means for analysing call data and reducing theusage allocation in a usage allocation record when said call dataindicates that a subscriber in a group sharing said usage allocationrecord has made a call in the mobile communications system, such thatsaid usage allocation record indicates the amount of said usageallocation remaining after said call.

[0020] Thus, by means of a common usage allocation record, the currentamount of usage allocation remaining may be readily determined eitherduring a billing period or at the end of a billing period.

[0021] According to a still further aspect of the invention there isprovided apparatus for generating billing data for subscribers in amobile communications system, said apparatus including data processingmeans comprising:

[0022] first means for associating a shared allocation of usage with agroup consisting of a plurality of subscribers; and

[0023] second means for processing call data and for reducing saidshared allocation when said call data indicates that a call has beenmade by any of said plurality of subscribers in the group.

[0024] By sharing usage allocations, a given usage allocation can bemore readily utilised in a given billing period, irrespective offluctuations of usage by an individual subscriber in a group.

[0025] According to a further aspect of the invention there is providedapparatus for generating billing data for subscribers in a mobilecommunications system, said apparatus including data processing meanscomprising:

[0026] first means for selecting a billing account;

[0027] second means for allocating a plurality of groups of subscribersto said selected account;

[0028] third means for allocating a plurality of subscribers to each ofsaid groups; and

[0029] fourth means for processing call data for each subscriberallocated to said billing account to generate said billing data for saidaccount; said billing data including a total charge for said account anda total charge for each said group.

[0030] Thus, a set of billing data for an account may be provided whichsets out the charge not only for the account as a whole, but also fordifferent groups of subscribers in the account, such as differentdepartments of a business concern.

[0031] Further features and advantages of the present invention will beapparent from the following description of preferred embodiments of theinvention, wherein:

[0032]FIG. 1 is a block diagram schematically illustrating a mobilecommunications network in accordance with an embodiment of theinvention;

[0033]FIG. 2 is a block diagram schematically illustrating a billingcentre in accordance with an embodiment of the invention;

[0034]FIG. 3 is a flow diagram illustrating procedures carried out bythe call billing centre of FIG. 2;

[0035]FIG. 4 is a flow diagram illustrating a call rating procedurecarried out by the billing centre of FIG. 2; and

[0036]FIG. 5 is a flow diagram illustrating a billing procedure carriedout in the billing centre of FIG. 2.

[0037]FIG. 1 shows a cellular communications network, such as a GSMnetwork, which is in itself known and will not be described in detail. Amobile switching centre (MSC) 2 is connected via communications links toa number of base station controllers (BSCs) 4. The BSCs 4 are dispersedgeographically across areas served by the MSC 2. Each BSC 4 controls oneor more base transceiver stations (BTSs) 6 located remote from, andconnected by further communications links to, the BSC. Each BTS 6transmits radio signals to, and receives radio signals from, mobilestations 8 which are in an area served by that BTS. That area isreferred to as a “cell”. A mobile communications network is providedwith a large number of such cells, which are ideally contiguous toprovide continuous coverage over the whole network territory.

[0038] The MSC 2 is also connected via communications links to otherMSCs in the remainder of the communications system 10, and to a publicservices telephone network (PSTN), ISDN lines, etc, which are notillustrated. The MSC is provided with a home location register (HLR) 12which is a database storing subscriber authentication data, and avisitor location register (VLR) 14 which is a database temporarilystoring subscriber authentication data for mobile stations active in itsarea.

[0039] When the user of the mobile station 8 utilises atelecommunications service provided by the mobile communicationsnetwork, for example by initiating a voice call, sending a fax, sendingdata, sending text messages, or retrieving voicemail, etc, a call detailrecord is generated in the network, which is sent to a billing centre16.

[0040] The call detail records include, amongst other information, theinternational mobile subscriber identity (IMSI) and the telephonedirectory number (MSISDN) used for the call, along with data allowingthe computation of a charge for the call. This data includes the dateand time of the beginning of the call, its duration, the nature of theservice provided during the call (voice, data, short messages, etc) thecalled party number, and in the case of packet services, the volume oftransmitted data. Sub- Monthly scrip- 1st handset charge per Number tionmonthly additional of users Shared peak off-peak type charge handsetallowed bundle n/min n/min 1 N N/2 1-2 60 mins 10 n 5 n 2 2 N N/2 1-3200 mins  9 n 4 n 3 3 N N/2 1-4 360 mins  8 n 4 n 4 4 N N/2 1-5 540 mins 7 n 3 n 5 7 N N/2  1-10 1000 mins  7 n 3 n 6 18 N N/2  1-25 2500 mins 7 n 3 n 7 36 N N/2  1-50 5000 mins  7 n 3 n

[0041] As indicated, seven subscription types are provided havingvarying charging details. The charges shown are in cost units N and nfor illustrative purposes.

[0042] Any number of subscribers (from a single subscriber to a group of50. or more if desired) may be allocated to a single subscription,depending on the subscription type held. In each subscription type, a“bundle” of pre-paid call time usage allocation is provided for useduring a single month. A monthly subscription charge is levied for thefirst subscriber according to the subscription type held, and a setmonthly subscription charge is charged for every further subscriberadded to the subscription. Subscribers pay call charges fornon-bundle-time calls at peak times, and off-peak times, according tothe subscription held.

[0043] From table 1, it will be apparent that the choice of a differentsubscription alters the characteristics of the subscription type asfollows:

[0044] 1. The monthly subscription charge for a single subscribersubscription generally increases.

[0045] 2. The monthly subscription charge for a group subscriptiongenerally increases.

[0046] 3. The number of subscribers allowed in a group subscriptiongenerally increases (from 2 to 50).

[0047] 4. The bundle of pre-paid usage allocation (call time) generallyincreases.

[0048] 5. The call charging tariffs, for both peak and off-peak calls,generally decrease.

[0049] It is also a feature of this embodiment of the invention that anaccount holder may have multiple subscriptions, including groupsubscriptions and/or individual subscriptions, in a single accountmanaged by the billing centre 16.

[0050]FIG. 2 illustrates features of the billing centre schematically.The billing centre includes a call detail record logging store 18, arelational database software application 20 and its associated datastore 22, a call rating software application 24 and its associatedtariff data store 26, a billing software application 28 and itsassociated subscription data store 30, and a billing report printingapparatus 32.

[0051] Each of the software applications 20, 24, 28 is implemented in anappropriate data processing means, such as a mainframe computer or acomputer workstation. The data store 18 may consist of magnetic tapedata storage, and/or other suitable storage media, such as hard disks.

[0052] Also connected to the relational database application 20 is a setof customer service workstations 34, allowing for on-line data input andretrieval of subscriber, group and account details from the relationaldatabase.

[0053]FIG. 3 illustrates procedures carried out in the billing centre16. The call detail records are received continually, in real time, fromthe MSC to which the billing centre is connected and logged in loggingstore 18, step 40. These logged call detail records are thenperiodically input in batches into the relational database 20/22.

[0054] The call detail records, once in the relational database 20/22,are then rated in date and time order by the rating application 24,referring to the tariff store 26 to attach an appropriate charge to eachcall detail record. The attached charge is stored in the relationaldatabase 20/22.

[0055] The relational database 20/22 holds not only call detail recordsbut also subscriber detail records, bundle records (to be describedbelow), group records and billing account records. The relationaldatabase holds subscriber data for each subscriber identifying thebilling account to which the subscriber belongs, and if the subscriberis an individual subscriber. details identifying the subscription typewhich the subscriber holds, or if the subscriber belongs to a group,data identifying the group to which the subscriber belongs. The grouprecords indicate the type of subscription held for the group. Therelational database is configured so that any details relating to abilling account held in the database may be retrieved by selecting theappropriate billing account, any details relating to a group held on thedatabase may be retrieved by selecting the appropriate group, and anydetails relating to a particular subscriber held in the database may beretrieved by selecting the appropriate subscriber.

[0056] Each bundle record is associated with a particular subscription,whether that is an individual subscriber subscription or a groupsubscription. Each bundle record holds data indicating an amount ofpre-paid allocated call-time usage (referred to as a call time “bundle”herein) allowed for the subscription during each billing period, anddata indicating the amount of that usage allocation remaining during abilling period. In this embodiment of the invention, the usageallocation is a duration of call time. In the case of asingle-subscriber subscription, the bundle is related to a singledirectory number (MSISDN) and may be used by that subscriber only. Inthe case of a group subscription, the bundle is related to a number ofdirectory numbers (MSISDNs) and may be used by any subscriber in thegroup in part or in whole.

[0057] In this embodiment no charges are made by the network operatorfor usage of the bundle time, and therefore it is desirable forsubscribers to utilise all of their bundle time during a billing period.

[0058]FIG. 4 illustrates the rating procedure carried out by the ratingapplication 24 for a single call detail record. The call detail recordis first analysed to determine whether the call made is of a standardcall type, step 50. For example, standard calls may include nationalfixed-line terminating calls. whereas calls made to other mobilestations, premium rate services or international calls will be treatedas non-standard, since they are generally more costly.

[0059] If the call type indicated in the call detail record isnon-standard, the rating application 24 proceeds to calculate a chargefor the entire call, by retrieving non-standard tariff charging detailsheld in the tariff store 26, step 54. When the charge has beencalculated, data indicating the charge is added to the call detailrecord, 56, to allow the call to be billed at a later stage.

[0060] If in step 50 the call is identified as a standard call type, itis determined that the call duration may be subtracted from anyavailable bundle time, rather than being charged for directly. In orderto identify the bundle record holding the appropriate usage allocationdata, the rating application 24 determines the directory number (MSISDN)from which the call was conducted, whereby the bundle record isidentified by association in the relational database 20/22, step 52.

[0061] If the bundle record indicates that all of the bundle timeoriginally available at the start of the billing period has been usedalready, the rating application 24 proceeds to retrieve data indicatingthe subscription type of the subscriber from the relational database20/22 and standard tariff charges for that subscription type from thetariff store 26, and thereby to calculate the charge for the entirecall, step 54. The calculated charge is added to the call detail record,step 56.

[0062] If however there is bundle time remaining, it is checked whetherthe bundle time remaining is greater than or equal to the duration ofthe call. If so, the duration of the call is subtracted from theremaining bundle time in the bundle record, step 58, and data indicatingthe bundle time used is added to the call detail record, step 60, foruse in subsequent billing of the call. No charge is attached to the calldetail record.

[0063] If the bundle time remaining is less than the duration of thecall, the remaining bundle time is subtracted from the remaining usageallocation in the bundle record (then no usage allocation remains) anddata is added to the call detail record indicating the bundle timesubtracted, steps 62 and 64.

[0064] Next, the charge for the remaining duration of the call iscalculated by retrieving the subscription type held in the relationaldatabase 20/22, and the appropriate standard charging tariff detailsheld in the tariff store 26, step 66. Data indicating the charge to belevied is then added to the call detail record, 68, for use duringsubsequent billing of the call.

[0065] At the end of a billing period, all of the call detail recordspertaining to calls conducted during the billing period are stored inrated form on the relational database 20.

[0066]FIG. 5 illustrates the procedure followed by the billingapplication 28 at the end of each billing period in order to generatebilling data to be transmitted to the billing report printing apparatus32.

[0067] First, the billing application 28 selects an account in therelational database 20/22, step 70, and the first group of subscribersin that account is selected in step 72. The first subscriber in theselected group is selected in step 74.

[0068] For the selected member, the billing application 28 retrieveseach of the call detail records held in relational database 20/22 forthe preceding billing period in turn and totals the charges to be billedfor that subscriber using the charge data added to each call detailrecord by the rating application 24, and by totalling the periodicsubscription charge indicated by the subscription data held in therelational database 20/22, using the subscription charge store 30, step76.

[0069] The billing application 28 also totals the bundle time used bythe subscriber during the preceding billing period, as indicated by thedata added to the subscriber's call detail records by the ratingapplication 24, step 78. The billing application stores data indicatingthe charge to be billed for that subscriber and the amount of bundletime used by the subscriber.

[0070] The billing application 28 then proceeds to perform steps 74, 76and 78 for each subscriber in the selected group, until charging andbundle time data has been totalled for each subscriber in the selectedgroup. Then, the charges stored for each subscriber in the group aretotalled and data indicating the total charge for the group is stored,step 80, and the bundle time used by each subscriber is totalled anddata indicating the total bundle time used by subscribers in the groupis stored, step 82. The procedure returns to step 72 if the accountconsists of a number of groups, until there are no more groups remainingin the account.

[0071] Next, the total group charges calculated in step 80 are totalledand a total charge for the account is calculated and stored, step 84.

[0072] In step 86, the billing details for the account are compiled,using the charges and bundle times calculated by the billing application28, and using other data in the call detail records retrieved by thebilling application 28. The billing details include the subscriptioncharges levied, the usage charges incurred, and the amount of thesubscriber's group's allocation of bundle time used, for each subscriberin the account, the total subscription charges levied, the total usagecharges incurred, and the total usage allocation used by each group, thetotal charge to be posted to the account, and individual callitemisation details indicating the date, time, duration, cost andterminating point for each call made by subscribers in the accountduring the preceding billing period.

[0073] Once the billing details have been compiled for an account, thebilling details may be transmitted to the billing report printingapparatus, 32. The billing report printing apparatus 32 formats thebilling details to generate an invoice for the account on one page, agroup billing report on one or more further pages, and an individualcall itemisation report on one or more further pages. The invoicespecifies the total charges for the account to be paid by the accountholder. The group billing report indicates for each group in the accountthe total subscription charges incurred for the group and the totalbundle time used by the group, along with the total subscription chargesand the total bundle time used by each subscriber in the group Thisallows the account holder to readily understand the charges incurred byeach group in the account. The individual call itemisation report showsthe date, time, duration, charge and terminating point for each callmade by every subscriber in the account.

[0074] The embodiment of the present invention described provides abilling apparatus, in the form of a billing centre, for example similarto that shown in FIG. 2, whereby charging structures allowing associatedgroups of subscribers belonging to the same account, and consisting ofvarious numbers of subscribers, to be allocated collective chargingtariffs, and/or a shared allocation of pre-paid usage. Furthermore, bycalculating the usage allocation for each group actually used by eachsubscriber in a group, and by the group as a whole, during a billingperiod, and indicating those figures in the billing report generated foran account holder, the account holder is readily able to monitor theusage of the pre-paid allocations for groups in the account. In case theaccount holder finds that one or more groups of subscribers in theaccount are not using their subscription effectively, the account holdercan ask the network operator to transfer the group to a differentsubscription type.

[0075] A billing centre for a mobile communications system is providedwhich allows groups of subscribers sharing a single account to beidentified both, during the call rating procedure, during which calldetail records are to add a charge to the call detail record, and/or toadd a usage of a pre-paid usage allocation to the call detail records,and during the production of billing details at the end of a billingperiod.

[0076] A relational database holds usage allocation records whichpertain either to a single subscriber, or to a group of subscribers. Thegroup of subscribers may consist of any of 2 to 50, or more,subscribers, depending on the subscription type held by the group.

[0077] It is to be mentioned that the elements of the billing centreillustrated in FIG. 2 need not be located at a single centre. Forexample, the billing data produced by the billing application 28 may betransferred to magnetic tapes and transported to a printing centre forprinting by the billing report printing apparatus 32.

[0078] In the case of subscriptions being taken through a serviceprovider, rather than the network operator, the call detail records heldin the relational database 20/22 for the proceeding billing period, oncerated, may be sent to the service provider for processing using abilling application belonging to the service provider. Alternatively,the billing details may be generated by the billing application 28, andthe billing details transmitted to the service provider for theproduction of billing reports by the service provider.

[0079] In the embodiment described above, the usage allocation consistsof a call time bundle. However, other usage allocations may be provided,such as a bundle consisting of a number of short messages, a number ofpages of fax transmission, an amount of data, etc. Furthermore, theusage allocation need not be pre-paid in entirety—the bundle resourceused may for example be charged at a reduced tariff.

[0080] It will also be appreciated that various other modifications andvariations may be employed in relation to the above-described embodimentwithout departing from the spirit or scope of the present invention.

1. Apparatus for generating billing data for subscribers in atelecommunications system, said apparatus comprising: data storage meansfor holding subscriber records for a plurality of groups of subscribers,each of said groups comprising a plurality of subscribers for which acombined subscription is held, said groups comprising different numbersof subscribers; and data processing means for analysing call data andapplying one of a number of different predetermined call chargingtariffs to a call made by a subscriber in one of said groups, independence on the group of which the subscriber is a member, in order togenerate charging data for said call.
 2. Apparatus according to claim 1,wherein said storage means is for holding billing account records, eachof said groups being associated with a respective billing account, andsaid processing means is for generating a combined billing report foreach said billing account.
 3. Apparatus according to claim 1, whereinsaid processing means is for relating a shared usage allocation tosubscribers in one of said groups.
 4. Apparatus according to claim 3wherein said shared usage allocation is an allocation of call time whichmay be used in part or in whole by any of the subscribers in the group.5. Apparatus according to claim 4, wherein said processing means is forreducing said allocation of usage when said call data indicates that asubscriber in said group has made a call.
 6. Apparatus according toclaim 5, wherein said processing means is for analysing said call datato determine whether said call falls within predetermined call typecriteria, and for reducing said allocation of usage when those criteriaare met, providing any of said allocation remains.
 7. Apparatusaccording to claim 5, wherein said processing means is for processingsaid call data to generate billing data indicating the total amount ofsaid allocation of usage used by said subscribers in said group during abilling period.
 8. Apparatus for generating billing data for subscribersin a telecommunications system, said apparatus comprising: data storagemeans for holding subscriber records for a plurality of groups ofsubscribers, each of said groups comprising a plurality of subscribersand said groups comprising different numbers of subscribers; and dataprocessing means comprising means for relating respective usageallocations to each said group, each said allocation being shared bysubscribers in the related group.
 9. Apparatus according to claim 8,wherein said usage allocations are each allocations of call time whichmay be used by any of the respective subscribers in the related groups.10. Apparatus according to claim 8, wherein said processing means is forprocessing call data to reduce one of said usage allocations for a callmade by any of the subscribers in the related group.
 11. Apparatusaccording to claim 10, wherein said processing means is for analysingsaid call data to determine whether said call falls within predeterminedcall type criteria, and for reducing said usage allocation when thosecriteria are met, providing any of said allocation remains. 12.Apparatus according to claim 10, wherein said processing means is forprocessing said call data to generate billing data indicating the totalamount of the group's usage allocation actually used by subscribers insaid group during a billing period.
 13. Apparatus according to claim 8,wherein said usage allocations have varying magnitudes.
 14. Apparatusaccording to claim 13, wherein a plurality of group types are defined,different said magnitudes being allocated to different group types andthe number of subscribers allowed in a group being dependent on thegroup type.
 15. Apparatus according to claim 14, wherein the number ofsubscribers allowed in a group generally increases with the magnitude ofthe group's usage allocation.
 16. Apparatus according to claim 8,wherein said telecommunications system is a mobile communicationssystem.
 17. Apparatus for generating billing data for subscribers in amobile communications system, said apparatus comprising: data storagemeans for storing subscriber records and usage allocation records, saidusage allocation records being shared by respective groups ofsubscribers, each said group comprising a plurality of subscribers; anddata processing means for analysing call data and reducing the usageallocation in a usage allocation record when said call data indicatesthat a subscriber in a group sharing said usage allocation record hasmade a call in the mobile communications system, such that said usageallocation record indicates the amount of said usage allocationremaining after said call.
 18. Apparatus according to claim 17, whereinthe processing means reduces the usage allocation in the same resourceallocation record when said call data indicates that a differentsubscriber in the same group has made a call in the mobilecommunications system.
 19. Apparatus according to claim 18, wherein theprocessing means attaches data indicating the amount of said reductionin usage allocation to the call data when the call data is processed.20. Apparatus according to claim 17, wherein said processing meansidentifies a usage allocation record associated with a subscriber bymeans of a subscriber identity number indicated by said call data. 21.Apparatus according to claim 20, wherein said subscriber identity numberis a telephone directory number, such as an MSISDN.
 22. Apparatus forgenerating billing data for subscribers in a mobile communicationssystem, said apparatus including data processing means comprising: firstmeans for associating a shared allocation of usage with a groupconsisting of a plurality of subscribers; and second means forprocessing call data and for reducing said shared allocation when saidcall data indicates that a call has been made by any of said pluralityof subscribers in the group.
 23. Apparatus according to claim 22,wherein said second means is for reducing said shared allocation onlywhen said call data indicates that a call falling within predeterminedcall type criteria has been made.
 24. Apparatus for generating billingdata for subscribers in a mobile communications system, said apparatusincluding processing means comprising: first means for selecting abilling account; second means for allocating a plurality of groups ofsubscribers to said selected account; third means for allocating aplurality of subscribers to each of said groups; and fourth means forprocessing call data for each subscriber allocated to said billingaccount to generate said billing data for said account; said billingdata including a total charge for said account and a total charge foreach said group.
 25. Apparatus according to any preceding claim, furthercomprising means for printing billing reports using said billing data.26. Apparatus, or a method, substantially as hereinbefore described, inparticular with reference to the accompanying drawings.